Putting Physics into Human Modeling

Thanks to the broad availability
of digital human modeling software, avatars are playing a more prominent role
in evaluating the manufacturing feasibility and safety issues surrounding both
product designs and assembly line ergonomics, mitigating the need for costly
physical prototypes. Yet while most
currently available avatars are digital representations of the static human
form, the University of Iowa's
College of Engineering's Center for Computer-Aided Design is taking
the concept of human modeling a step further with Santos, an avatar that is a
high fidelity, biomechanically accurate model of a person, including the
physics of bone and muscle.

The combination of the
biomechanical musculoskeletal model along with predicative dynamics technology
means Santos just doesn't just mimic biomechanical motions - the avatar is
being designed to predict motion and to react to movements on its own. Santos
doesn't just sit in the cockpit of a tank or move a piece of equipment from
Point A to Point B on the factory floor so engineers can evaluate reach and
other ergonomic factors. Instead, the
digital avatar's physics-based approach can deliver feedback on how a certain
type of task or combination of movements will impact a human's level of
fatigue, speed, strength and torque over a period of time.

"We're really trying to understand
how a human behaves from a biomechanical point of view - why they take this
particular motion or posture, and can a person really complete this task,"
explains Karim Abdel-Malek Ph.D., professor at the University of Iowa's Dept.
of Biomedical Engineering, director of the Center for Computer-Aided Design and
director of the U.S. Army's Virtual Solider Research (VSR) program, the
birthplace of Santos, which is funded in part by the U.S. military. "Any time
you're carrying a box from the ground up or swinging an engine - anything to do
with motion and dynamics - there are moments of inertia involved that are not
accounted for if you're just doing static analysis (of human modeling). The new
thing is physics, which adds a real-world element of reality to it."

Santos Lightens Soldiers' Loads

The
Santos project got its start in 2004 at the University of Iowa and through the
years has received a variety of funding from partners, including several of the
major automotive manufacturers, among them, Ford and General Motors,
in addition to other Fortune companies like Caterpillar to its most
prominent proponent - the U.S. military. This April, in fact, the VSR team was
awarded a five-year contract valued at up to $8.6 million from the U.S. Navy
for Santos' work related to a project aimed at helping military personnel carry
lighter loads into combat. The project, formally known as "Enhanced
Technologies for Optimization of Warfighter Load" (ETOWL), is being conducted
for use in both the Navy and Marines, using Santos to simulate the effect of
equipment loads on military personnel from the standpoint of mobility and
physical stress without having to place real human fighters in the field. Among
the project's deliverables: A set of computational modeling tools along with
easy-to-use planning tools that leverage the models to enable small-unit
leaders to evaluate the trade-offs of different equipment profiles across a
squad for better decision making.

Given the fact that the military, just like
mainstream business, is dealing with budget shortfalls, virtual prototyping and
avatars like Santos are key to designing optimal gear without adding millions
of dollars in costs or years of prototyping time to the development cycle. "The
very top generals have identified modeling and simulation as the key component
that will save their design cycles cost and time," says Abdel-Malek.

Depending on the project, the
different military branches will be able to outfit Santos with different gear,
a war-time backpack, for example, and test such factors as how carrying the
pack reduces a soldier's mobility or what kind of physical stress is created by
carrying the load for an extended period of time. Traditionally, the military
has done this kind of testing with physical prototypes of proposed equipment on
real-world soldiers, oftentimes, in the field.

"It takes a whole team of people
to make decisions on this stuff and before they make any kind of decision, they
test the gear on different types of bodies," Abdel-Malek says. "It takes
forever to do that and it's difficult to make design changes and then go back
and retest. With virtual prototyping, we give them a tool that saves them an
incredible amount of time. And by predicting motion, they don't have to bring
humans in."

Santos at Work

In
anticipation of similar needs in the corporate market, the VSR university team
in 2008 spun off Santos Human
Inc., a company charged with bringing
a commercial version of the digital human modeling software to the commercial
market. Honda, one of Santos Human's corporate partners and a beta tester of
the technology, currently employs digital human modeling software as part of
its V6 implementation of Dassault Systémes'
CATIA 3D CAD and DELMIA digital manufacturing software. Despite the utility of
these programs, the physics-based Santos will up the ante in terms of
evaluating fatigue factors or determining if a bend or reach is too much over a
period of time during an employee shift, according to Bryan Beeney, engineering
coordinator at Honda of America's East Liberty plant.

"The physics-based approach will
show a reaction as a human body does," he says. So, for example, if you put
weight on the body, Santos can display what the human body will do to
accommodate the additional weight - perhaps spread out the feet to find balance
or lock in the hips to hold up the weight. "With a lot of these programs, you
can load 80 pounds on an avatar and nothing changes," he explains. "The data in
the background changes, but visually, the avatar is static."

Ford, another Santos partner, has had great
success with reducing factory floor injuries by employing traditional human
modeling programs, including Jack
from Siemens PLM Software. Today, digital Jack or Jill avatars assemble
vehicles in the virtual world while a team evaluates manufacturing feasibility
and assembly sequence, all well before any physical parts are produced or tooling
or workstations configured. While this approach has allowed Ford to reduce
ergonomic issues related to its assembly operations far earlier in the R&D
process when it is far less costly to reconfigure designs, there is even
greater opportunity with Santos, according to Allison Stephens, Ford's global
technical leader in Assembly Ergonomics. Specifically, Santos will allow Ford
to evaluate the long-term effects on tissue breakdown as it relates to
repetitive tasks on the factory floor over the long term, which as Stephens
says, takes things to a whole new level.

"The model is smart enough,
because it's physics-based, to calculate how much muscular force is needed to
climb into a car, hold up an instrument panel or reach over to the center of a
vehicle with a power tool to make something secure," she explains. "This is not
about comfort, but rather more about can I expect someone to do that once a
minute without going to the point of tissue damage or muscular fatigue."

In the days prior to any kind of
simulation, Stephens' team would average around 300 design changes per vehicle
due to ergonomic issues related to factory floor operations, costing as much as
$45,000 per change because they were caught and made far into the design cycle.
Static simulations through the use of Siemens' Jack have helped Ford reduce
that number by 90 percent, but Santos can help push it even further. "Even
though we're down to only 30 issues (per vehicle), we're still getting injuries
on the plant floor because that requires more complex motion evaluation,"
Stephens explains. Long term, she hopes to keep Siemens' Jack on hand for
static hand clearance and reach evaluations while leveraging Santos to do more
complex and full simulations to understand the cumulative impact on auto
workers.

While Stephens is hopeful about
Santos' promise, she admits there are still nagging technical hiccups that
prevent the software from being exploited to its full potential. Abdel-Malek,
acknowledging the shortcomings, says we're likely to see significant progress
within the year that will ready Santos for a prime-time appearance.

"The
environment is so well-prepared now (for this kind of technology) with all of
the understanding of avatars, gaming and Hollywood," he says. "There's been an
incredible boost in terms of understanding what it is and how it can help."

I applaud Santos and their progress with biomechanically accurate modeling and simulation of (physics-based) human activities. Wow!

The biggest improvement, in my book, is the creation of a tool that saves an incredible amount of time (and therefore cost). And by predicting motion, you don't have to bring humans in.

Human testers and the medical costs that go along with botched empirical testing (...sorry about your back, man) will be seriously reduced since you will be able to zero in on what is optimal before giving it to a real person to try out.

A few weeks ago, Ford Motor Co. quietly announced that it was rolling out a new wrinkle to the powerful safety feature called stability control, adding even more lifesaving potential to a technology that has already been very successful.

It won't be too much longer and hardware design, as we used to know it, will be remembered alongside the slide rule and the Karnaugh map. You will need to move beyond those familiar bits and bytes into the new world of software centric design.

People who want to take advantage of solar energy in their homes no longer need to install a bolt-on solar-panel system atop their houses -- they can integrate solar-energy-harvesting shingles directing into an existing or new roof instead.

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